In computer networking, network address translation (NAT) is the process of modifying network address information in datagram (IP) packet headers while in transit across a traffic routing device for the purpose of remapping one IP address space into another.

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FTP Traffic routing through NAT prevents me from logging in

I need to send all FTP traffic to a particular server from a NAT. Server A connects via FTP to an IP which is routed to the NAT and then over a VPN. That traffic then comes back and gets routed from ...
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90 views

strongswan packet get natted when ufw is enabled

I'm using strongswan 4.6.4 to connect road warriors to my server (ubuntu 13.10), which is natted behind a firewall. left=%defaultroute leftsubnet=10.10.1.0/24 right=%any ...
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199 views

Dead-simple Juniper firewall hairpinning [closed]

I have a SRX100 firewall running JunOS 12.1. I have a WAN interface proxy ARPing ten or so static routable IPs. I have a LAN interface on a simple class-C subnet (we'll call it 192.168.0.x). I'm using ...
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59 views

OpenVPN running on Internet Gateway, so all private clients can access VPN with no config

Our LAN connects to our office gateway machine (192.168.1.1), which is connected to the Internet. I have setup NAT/Masquerading for this purpose with no issue. We also use OpenVPN to connect to our ...
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57 views

Cisco IOS log packets dropped due to no NAT entries?

I use access list logging currently, and update the access list to match the NAT table, and then the access-list deny any any log command is used for logging packets that were not allowed. However, I ...
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1answer
181 views

Access Apache VirtualHost from localhost

I have a DirectAdmin setup with Apache on a server which is behind NAT. Everything is working correctly when accessing a VirtualHost from outside the machine (either through the Internet and the ...
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1answer
45 views

Should we accomodate a customer asking us to NAT servers behind new PUBLIC IPs within a VPN?

We're a SaaS provider, setting up a IPSec VPN between our data center and a customer's site so they can directly access their hosted database server from their LAN. Instead of exposing our internal ...
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1answer
171 views

how to forward proxy requests using iptables

I've this schenario ----------------- ---------------- ---------- | SERVER A | ---(port:2128)> | PROXY | ---> | INTERNET | | (10.30.1.1) | ...
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1answer
78 views

Cisco ASA 5510 nat

In my infrastructure, I natted a server on a Public IP address. Please note, the server is reachable from any outside network. My access rules are good. My isssue is from the internal network, I'm ...
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1answer
3k views

Asterisk and SIP behind NAT

I am trying to Setup an Asterisk-Server to accept calls from a client in an other Network. The Server and the client are behind an NAT. I have already activated STUN on the client, but I am still ...
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2answers
49 views

Forwarding all connections to different address

I have a script that tries to connect to rabbitmq using default url and port (localhost:5672). Is it possible to make linux redirect all connections to this url and port to different server? I am ...
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1answer
194 views

Linux iptables DNAT stops working after some time

3 down vote favorite I have a strange behaviour in my server setup. It looks like that. client1 192.168.11.2/24 <----> 192.168.11.7/24 (br1/vlan1) Server 192.168.21.1/24 (br21/vlan21) <---> ...
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2answers
303 views

Portforwarding with IPTABLES and Remote IP detection

I was able to forward 80 port from my primary server 192.168.90.1 to the second one 192.168.90.2 with IPTABLES The primary server has a public address X.X.X.X so I forwarded X.X.X.X:80 -> ...
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1answer
2k views

strongSwan setup where both sides are behind NAT

I'm trying to setup a strongSwan server in my home and connect to it from another network. Let's say sun is the VPN server and venus is the client. Both sun and venus are behind NAT networks. sun is ...
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2answers
141 views

Forward web request to another computer

I have one notebook and two servers: ip = 172.17.0.2 (I have installed nginx here) ip = 172.17.0.3 (There is nothing here, but I can ping 172.17.0.2 from here) I open browser on my notebook, open ...
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1answer
118 views

How do I know that my TCP connection is safe from the Firewalls/NAT?

Being on the Azure cloud, I found that the firewalls there drop connections between the Web server and the database quite often. Mostly when there was some inactivity, I think something between 5 and ...
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2answers
379 views

Internet VPN Tunnel with a server behind NAT

Let's say someone would like to route all their traffic traffic though some PC in another country (to unblock some sites). However, this PC is a usual Windows 7 PC behind a router with NAT, which ...
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1answer
152 views

How to apply port forwarding with iptables on existing connections?

For load balancing purposes, occasionally our servers forward requests to a different port; The default port for our service is port 5000. This is the code used: iptables -t nat -A PREROUTING -p tcp ...
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1answer
218 views

Configure atftp server to reply on port 69

Problem : I'm facing to a problem with TFTP server and Cisco 79XX IP phones. When on a local network, everything is working fine, but when the TFTP server is on a public server (and phones inside a ...
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18 views

client does not respond server's syn_ack package

pc to access the server through a NAT device。 client has successfully established a tcp socket with server using this port , and the server's interacted with the message well, socket has been closed ...
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1answer
360 views

How can I know if NAT instance is becoming a bottleneck

I'm running my own NAT instance inside of an AWS VPC. I want to make sure that the NAT instance will not be a bottleneck and to that end would like to set my own expectation for when to scale to a ...
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160 views

Simulating a client behind a NAT in Virtual Box

I am trying to simulate a client behind a NAT using Virtual Box. I have a host machine let's say with an IP address 130.0.0.1. I create a virtual machine (let's call it VM1) running Ubuntu 12.04 with ...
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157 views

Load-balancing PPTP connections

I'm trying to load balance two PPTP connections, connected to the same server. I use the following script, but there is no send and receive via PPTP connections. What part am I doing wrong? Are there ...
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2answers
199 views

Iptables MASQUERADE: What is the advantage/disadvantage between these two commands? [closed]

What is the advantage/disadvantage between below 2 commands: iptables -t nat -A POSTROUTING -o eth0 -s 10.0.0.0/16 -j MASQUERADE AND iptables -t nat -A POSTROUTING -j MASQUERADE Some Background ...
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1answer
308 views

iptables DNAT port forward to another machine on LAN

I am trying to implement iptables forwarding rules in order to internally redirect packets coming through a specific port. My machine is running under the distribution Ubuntu Server 12.04.3, with UFW ...
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2answers
3k views

AWS VPC + IPtables + NAT: Port Forwarding is not working

Yesterday, I posted a question here but I think was not clear enough in my words. BTW, This question is not a duplicate. I have AWS VPC Setup as below. GOAL/PROBLEM: SSH to Server A from internet. ...
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2answers
236 views

IPtables: Forward port to another host is not working

I am trying out something so this is my test setup: Setup: I have AWS VPC with a public and private subnet. I have a host in public subnet with a public IP address (say Host A) I have a host in ...
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1answer
355 views

IPTables and SNAT for just two ports

I want to set up some NAT policies so that certain machines will only have outbound access to http/https. They should not be able to do port scans or anything else from their machine. Currently my ...
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230 views

Repair RRAS and NAT on Windows Server 2008 R2

We have a Windows Server 2008 R2 server with RRAS installed and configure with VPN and NAT. NAT stopped working and when I checked, IPv4 is missing . I've tried re-installing RRAS but it just ...
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1answer
37 views

Can't see Webserver from LAN - NAT Issue?

I just got a ZyXEL USG50 and it's more complex than I'm used to. Traffic from WAN is going to my websever as desired thanks to a firewall and NAT rule. The problem is, when trying to request a ...
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1answer
5k views

Cisco ASA 5505 - NAT or Port Forward for SIP / VoIP ver 8.4

I just had an NEC PBX installed that lets me use SIP trunks for VoIP services, My gateway is a Cisco ASA 5505 running 8.4 and I only have one public/static IP Addresses. So far, my trunks are ...
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1answer
337 views

Apache2 server (behind Zyxel USG 100 NAT/Firewall) with vhost does not log real clients ip addresses

SOLVED To allow the Zyxel USG 100's NAT to forward untouched packets to my web server i edited the policy route of the Zyxel. Zyxel -> Configuration -> Network ->Routing -> Policy Route ...
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105 views

Port corruption using iptables NAT on Enterprise Linux 6

I am trying to setup a captive web portal redirect on CentOS using the following configuration: This configuration works for the first few packets, but then suddenly the destination port is corrupted ...
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1answer
1k views

libvirt and network filtering with nat - iptables overrides

At first, I want to say: I know, it was done initially wrong and I want to avoid doing everything again from the scratch because of general downtime. I am running libvirt/KVM on RHEL. I've got VM ...
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2answers
45 views

IIS and Apache hosting together

I know similar questions have been asked already, but mines a little more unique. I work for an internet/networking company. We build and host websites, as well as provide internet and network setups ...
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2answers
229 views

INPUT, OUTPUT or Forward Chain

I'm using a linux box as a router: The Box has 2 public ips and local ip, i'm using natting to allow local users to access the web. When a local user access the web, source natting happens here, ...
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1answer
420 views

iptables and port redirection (nat)

I am trying to build a router from ubuntu 12.04. What I am trying to do is, by using 1 public IP (100.0.0.100) and I tons of local ips like 10.0.0.0/16, to map each port to one ip like; ...
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1answer
399 views

How to Setup Linux Server As A Router with NAT

We have a simple router which has NAT of symmetric type, but because this router doesn't provide us with any debugging interface, we cannot figure out if a specific packet reaches the NAT or not. ...
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2answers
417 views

Accept incoming connection from a second gateway

I searched a lot about the question, but can't find solution for my situation. We've got a Windows 2003 server that runs Advantage Database Server (ADS) through which our site connects to our ...
2
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1answer
256 views

Redirection with natd flags on FreeBSD

I am trying to setup a basic NAT server. I want all traffic coming from the outside world to the NAT server to be redirected to another machine, where I have a lipcap service running to parse this ...
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0answers
125 views

How to set mark on packet when forwarding it in nat prerouting table with rp filter 0?

I have a serious problem with my server ubuntu 13. I have two ADSL lines and an internal network as follows. i.imgur.com/v4ddHXf.png (URL IMG) IP redirections made ​​two because there are two older ...
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2answers
293 views

NAT vs Proxy server

I have installed squid proxy server to hide our network ips after some time it becomes slow then I read through NAT rules to achieve what I want by proxy server. As per this link the difference ...
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2answers
304 views

Router/Gateway with host-header capability

Can anyone direct me what to look for to get a Router / Gateway / Firewall for my home-office enviroment to be able to run multiple e.g. Webserver on port 80, with one public ip. I know it can be done ...
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1answer
206 views

iptables alternative for nat in windows

When setting up a comms server I usually use iptables in linux to forward any incoming connections on a particular port to another server, e.g. Chain PREROUTING (policy ACCEPT) target prot opt ...
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74 views

Multiple routes and gateways with NAT

My setup is a VM host with two network interfaces where I want to use one as private/internal and the other one as public (which will get a public address on the host), where all the NAT magic to the ...
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1answer
692 views

iptables port forwarding to vmware workstation guests on NAT vmnet [closed]

Try as I might, I can't get this to work now for 2 days. Your move, internet. I want iptables to transparently forward (localhost) 192.168.1.40:2222 to 192.168.2.22:22 and I don't want ...
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1answer
87 views

Cisco ASA 5505: Created a faulty NAT rule. Can't reach the ASA

I was trying to create a NAT rule to reach my internal web server from inside the LAN. Something must have gone wrong. Now when i try to reach the ASA through https://192.168.1.1 the response is from ...
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2answers
91 views

IPtables NAT puzzler: Why is traffic from the firewall host being NATed even though it's not coming from one of the prescribed source addresses?

I run a small network where a linux web/mail server also provides NAT for a collection of windows boxes. One of these windows machines is apparently misbehaving (ZeroAccess botnet even though I can't ...
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2answers
279 views

VMWare NAT releasing SYN packets from guest but not admitting SYN/ACK packets to guest

VMWare Server 2.0.2 Host OS is Windows Server 2008 R2 Standard Guest OS is Windows XP I am using VMWare VMNet8, the NAT network. The VM guests can't see out to the network around the VM host. Packet ...
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1answer
272 views

Ubuntu Server / IpTables / Port Forwarding / NAT

I got referred here from StackOverflow. I'm using IpTables to forward an incoming port on one server to an external server (not on LAN) and the same port. The problem I'm having is that I have to use ...